In early April, the Paris-Orly Airport began using a new 6500 m2 (1.6 ac) filter marsh to treat stormwater runoff. According to Aéroports de Paris, the marsh is the only system of its kind to be installed at an airport. The airport’s current stormwater treatment system captures 3 million to 5 million m3 (800 million to 1.3 billion gal.) annually. The marsh, planted with reeds, will supplement the physical and chemical treatment carried out by the airport’s current treatment system. It will help to treat winter chemicals used to de-ice aircrafts and runways.
During the winter, airport stormwater will be collected in a new 13,000 m3 (3.4 million gal.) buffer tank where bacteria will begin to break down winter chemicals. After 24 to 48 hours, the water will be transferred to the marsh. The water filters through sand and aggregate while the plants oxygenate the mineral filter. Water is immediately absorbed by the sand and does not stagnate. Sensors have been installed at the marsh outlet to determine the water quality. If necessary, water can be returned for a second treatment cycle in the filter marsh.
The marsh was designed by ADPI, the engineering subsidiary of Aéroports de Paris, in collaboration with Antéagroup (Antwerp, Belgium) engineering consultants, and was developed by Lyonnaise des Eaux.